FAST issues.

[foxspy]

Hey everyone,

I have two questions about my B2B FAST w/ wide band.

First:
I did all my tuning in the fall/winter and now that the air temps are higher, my wideband is reading lean and the correction % is up in the 10-15% range. I've heard that I shouldn't mess w/ the air temp vs enrichment table cause the FAST does it automatically. But I'm thinking that the FAST is taking fuel out due to the warmer air, but is taking too much out. My IAT are about 50* above ambient, it's a N/A BBC. So should I just adjust the IAT vs enrichment table so I'm adding fuel when the air gets warmer?

Second:
This question is regarding the main dash board. The MAP AE readout is "0" and is in red, as well as the "Cylinders", it reads 8 but it's in red as well.

What does that mean?

Thanks for the help.

 

[norbs]

I would contact fast on this. But it can't hurt to experiment on this and see what improvements you can come up with. But usually more heat needs less fuel, as the density is decreased?

 

[bruce]

I would contact fast on this. But it can't hurt to experiment on this and see what improvements you can come up with. But usually more heat needs less fuel, as the density is decreased?

Up until you need to start needing to use the fuel for in cylinder cooling.

*Fooling* with it can melt a motor down, as well if it's wrong, not *Fooling* with it can. For a not to radical N/A I can see not needing much tuning with it, but once you get to a Turbo application, and elevated MATs, then, IMO, it would be hard to say leave it alone.

For me, it seems to vary some with the *brews* of fuels out there, the *curve* seems to somewhat match the low end boiling point levels of the various fuels. *Curve* meaning when the correction, knees over for when you need to start richening things up again.

But, hey I don't run 9s so feel free to ignore me.....

 

[TurboTR]

I wonder why your IAT is so much above ambient? Seems like you could pick up alot of power by dropping the IAT some ~ 50 deg to near ambient

TurboTR

 

[foxspy]

I wonder why your IAT is so much above ambient? Seems like you could pick up alot of power by dropping the IAT some ~ 50 deg to near ambient

TurboTR

I just have an open element filter w/ the IAT sensor in the housing for the filter. So I don't have any kind of "cold air induction" or anything. Once I get moving down the highway, the IATs drop alot.

 

[foxspy]

I would contact fast on this. But it can't hurt to experiment on this and see what improvements you can come up with. But usually more heat needs less fuel, as the density is decreased?

The density has decreased. The DA lately has been 3200ft, when I tuned it originally, the DA was probably around 1400ft.

 

[QuickWrench]

...I've heard that I shouldn't mess w/ the air temp vs enrichment table cause the FAST does it automatically. But I'm thinking that the FAST is taking fuel out due to the warmer air, but is taking too much out...

I've heard that same thing, and those people get smacked. That's just silly.

If you drive the car on the street, this table should definitely be used. At the track, yes...I'd go without these corrections. But tooling around the street without some temp correction is going to force the ECU to make constant, large corrections from the base tables to correct for ambient temps.

 

[norbs]

Have you tried alpha_N mode? YOu can use the map sensor to compensate for atmospheric pressure i think. Alpha-N is a whole new ball game though have fun Main advantage is you can put the biggest cam that you can fit into the block and it will idle

 

[foxspy]

Have you tried alpha_N mode? YOu can use the map sensor to compensate for atmospheric pressure i think. Alpha-N is a whole new ball game though have fun Main advantage is you can put the biggest cam that you can fit into the block and it will idle

I shouldn't need Alpha N mode, my cam is only a small hyd roller, 242/248@.050", .541/.562 lift.

 

[gewroo]

I've heard that same thing, and those people get smacked. That's just silly.

If you drive the car on the street, this table should definitely be used. At the track, yes...I'd go without these corrections. But tooling around the street without some temp correction is going to force the ECU to make constant, large corrections from the base tables to correct for ambient temps.

According to FAST, their speed density algorithm automatically accounts for changes in inlet air temperature according to the ideal gas law (PV=nRT). Modifications via the air temp correction table are generally not recommended unless needed for cooling as Bruce said. With this in mind, the air temp sensor should be in the manifold (charge air) for speed density applications. This is especially true for forced induction.

 

[Reggie West]

You have all the tools there to make changes if necessary.

I would data log about 2 minutes worth of logs and make changes to the logs based on that.

Set up the log to read which inputs you want. For instance,A/F ratio, timing, Wide band correction if you dont already have a dashboard set up.

Let the logs tell you what is going on but I would bet that if the altitude has changed that much you can trim some fuel out of it and the motor will be much more responsive.

Right now you have a map set up for more fuel than you need. Good luck

 

[S351 R]

voltage

What does your voltage look like when it's hot? Heat creates resistance in all those electrical components, and may impact large injectors at idle/light throttle conditions. At least this is what happens to me. The hotter it is, the more unhappy my idle and throttle response are. An enrichment at 140*+ air temp helped band-aid my drivability in traffic. (What I really need to do is move some of that heat out from under the hood...)

 

[Otto J]

You could also move the sensor to a cooler place under the hood as it is not critical for fuel trim,Heat soaking it in an air filter gives a poor actual reading, could probably run it in the cowl area.